Press-in Part Double Knurl Rotational Fixation
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Solution Overview
Problem
Press-fit parts often experience insufficient rotational fixation due to inadequate material flow and deformation, especially with hard workpiece materials, leading to insufficient rotational load capacity and potential twisting.
Innovation Solution
The press-fit part incorporates at least two different knurls with varying tooth densities and shapes, allowing better material engagement and deformation during pressing, ensuring twist-proof anchoring even with unfavorable material flow behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single knurl is used on the press-in part, then the structure is simple, but the rotational fixation is insufficient especially with hard workpiece materials
Solution Approach 1:
The single knurl structure is divided into multiple knurls (first knurl and second knurl) with different geometries. The first knurl has a first tooth density and the second knurl has a second tooth density, creating segmented engagement zones that collectively improve rotational fixation while maintaining reasonable structural complexity
Solution Approach 2:
Different sections of the shank are given different knurl characteristics - the first knurl region has different tooth density and geometry than the second knurl region. This local differentiation allows each knurl to engage the workpiece material in a complementary manner, improving overall rotational fixation reliability
2Strength
If the workpiece material is hard, then the workpiece strength is high, but the material flow during pressing is insufficient leading to poor knurl engagement
Solution Approach 1:
The invention changes the geometric parameters of the knurls (tooth density, tooth shape, knurl diameter) to optimize engagement with hard workpiece materials. By varying these parameters between the first and second knurls, the system adapts to the limited material flow characteristics of hard materials, ensuring reliable engagement
3Reliability
If the knurl tooth density is high, then the rotational fixation is improved, but the material flow between teeth is restricted
Solution Approach 1:
The knurling is segmented into multiple zones with different tooth densities. The first knurl and second knurl have different tooth densities, allowing one region to provide rotational fixation while another region facilitates material flow and engagement, resolving the contradiction between fixation and material flow
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances rotational fixation and load capacity by coordinating knurl geometries to engage the workpiece material effectively, providing improved anchoring against torsional forces.
Implementation Method 1
there is typically a flow of material in the area of the walls of the recess during the pressing process
Implementation Method 2
the knurls cut into the walls of a recess provided for pressing, and thus prevent twisting of the press-fit part
Data Source
AI summary
The invention relates to a press-in part (1) for pressing a workpiece into a recess. Said press-in part comprises a shaft (10) for introducing into the recess and subsequently pressing therein. Said press-in part further comprises a head part (11) integrally joined to the shaft and protruding out of the workpiece after pressing the press-in part. Said press-in part is characterized in that the shaft comprises at least two different knurls (21, 22) engaging with the material of the workpiece after the press-in part is pressed in the recess, and rotationally fixedly connecting the press-in part to the workpiece.